To implement a fully automated process for making high-precision product is becoming the focal point for any future machinery as such high-precision product is becoming more and more miniaturized. It is noted that in the foreseeable future, the crave for ultra precision dies or parts in industries, such as personal portable 3C products, optoelectronic communication and bio-medication, will be growing unstoppably and thus the implementations of the Micro System Technology (MST) for making such ultra precision products are developing rapidly. However, when it come to machine a ultra-precision product, the complexity as well as the design of the ultra-precision product is restricted by the precision of its machining process, that is, the capability of the machinery implementing the machining process. Therefore, until now, it is still a costly effort to integrate a variety of machining processes in an integration mechanism just for manufacturing a high-precision product.
The machining of wire electrical discharge machine (WEDM) is one of the most accurate non-conventional manufacturing processes available for creating complex or simple shapes or geometries within parts and assemblies. WEDM works by eroding material in the path of electrical discharges by forming an arc between a wire electrode and a work piece that it is freed from the problems troubled by those conventional cutting machinery, such as cutting stress and electrode wearing. WEDM manufacturing is a very desirable manufacturing process when it comes to cutting some of the hardest material used in the industries in high accuracy.
Please refer to FIG. 1A and FIG. 1B, which are respectively a three-dimensional view of a conventional wire electrical discharge machine and a partial view thereof. The conventional wire electrical discharge machine (WEDM) 100 of FIG. 1A comprises: a motion platform 110, a sink 120, a workbench 130, a jib 140, a lower head 150, an upper head 160, a column 170 and a motion module 180. In which, the motion module 180 further comprises: a horizontal moving unit 182, capable of moving on a surface defined by a Cartesian coordinate system of U-axis and V-axis whereas the U-axis and V-axis of the Cartesian coordinate system are parallel respectively to the X-axis and Y-axis of another Cartesian coordinate system defining the working surface of the motion platform; and a vertical moving unit 184, capable of moving along a Z-axis which is vertical to the two surfaces defined by the U-, V-axes and the X-, Y-axes. As shown in FIG. 1A, the sink 120 is mounted on the motion platform 110 so that it can be brought to move horizontally by the motion platform 110. Furthermore, the workbench 130 is configured inside the sink 120 that is used for securely fixing a workpiece thereon.
In FIG. 1A, the sink 120 is configured with an opening for the jib 140 to pass therethrough and into the sink 120. It is noted that the gap between the jib 140 and the sink is sealed by the use of a dynamic leak prevention device. Moreover, the two ends of the jib 140 are connected respectively to the lower head 150 and the column 170; and the upper head 160 is disposed at a position over the lower head 150 while enabling the motion module 180 to be disposed at a position between the upper head 160 and the column 170.
WEDM works by eroding material in the path of electrical discharges by forming an arc between a wire electrode 190 and a workpiece, and during the cutting, both the workpiece and the wire electrode 190 are submerged in the sink 120 where they are flushed by ionized water. Generally, the wire electrode 190 is disposed passing through the upper head 160 and the lower head 150 and then entering the jib 140 where it is guided toward the waste tank in the column 170, by that it is able to machine the workpiece continuously.
Moreover, in a machining operation, the jib 140, the lower head 150, the upper head 160 and the column 170 as well as the motion module 180 are all fixedly secured while adjusting the relative position of the workpiece with respect to the wire electrode 190 by the movement of the work platform 110 as the sink 120 is going to be move along with the moving of the work platform 110 and thus brought the workbench 130 as well as the workpiece disposed thereon to move correspondingly. It is noted that the horizontal moving unit 182 and the upper head can be moved for achieving machining angle adjustment or top and bottom different machining.
As the sink 120 is designed to move relative to the jib 140, it is important to configure a dynamic leak prevention device at the joint between the jib 140 and the sink 120 for preventing leakage. However, as the dynamic leak prevention device shall move along with the movement of the sink 120, the dynamic leak prevention device can in some ways resist the sink to move if it is designed to perform a strong seal by that the precision of the sink movement is uncontrollable and thus it is difficult to perform a precision machining upon the workpiece. On the other hand, if the seal is poor, the leaking of the ionized water is going to cause the WEDM 100 from working effectively. In addition, as the sink 120 is mounted on the work platform 110 and moved thereby, the weight of the sink 120 along with the ionized water filled therein will hamper the movement of the work platform 110 in a manner that the positioning accuracy of the work platform 110 is reduced, not to mention that it will require more power just for driving the work platform 110 to move.
Please refer to FIG. 2A and FIG. 2B, which are partial views of another convention wire electrical discharge machine operating in different machining angles while the WEDM is a wire-cut machine provided by Swiss AGIE company. For clarity, only the portion of the WEDM including its upper and lower hands and the connection arm are depicted. In FIG. 2A and FIG. 2B, the upper head 210, the lower head 220 and the connection arm 230 are integrated and assembled into the C-shaped structure 200 which can be suspended on top of the sink in a manner that it can be lowered and thus submerged in the water filled in the sink.
In the abovementioned WEDM, its wire electrode 240 is designed to follow the guidance of a channel formed in the connection arm into a waste tank by that the relative movement between the connection arm and the sink is prevented. However, by the use of the aforesaid C-shaped structure 200, the WEDM will require to be installed with many rollers for guiding its used wire electrode to maneuver around the sink so that it is not only technically more complex and difficult, but also is more costly for constructing the foregoing C-shaped structure 200.